In recent years, autonomous robots, including Xavier, Martha 1], Rhino 2,3], Minerva, and Remote Agent, have shown impressive performance in long-term demonstrations. In NASA's Deep Space program, for example, an - tonomous spacecraft controller, called the Remote Agent 5], has autonomously performed a scienti?c experiment in space. At Carnegie Mellon University, Xavier 6], another autonomous mobile robot, navigated through an o?ce - vironment for more than a year, allowing people to issue navigation commands and monitor their execution via the Internet. In 1998, Minerva 7] acted for 13...